Rec. ITU-R BT.470-51
RECOMMENDATION ITU-R BT.470-5[*]
CONVENTIONAL TELEVISION SYSTEMS
(Question ITU-R 1-3/11)
(1970-1974-1986-1994-1995-1998)
Rec. ITU-R BT.470-5
The ITU Radiocommunication Assembly,
considering
a)that many countries have established satisfactory monochrome television broadcasting services based on either 525-line or 625-line systems;
b)that a number of countries have established (or are in the process of establishing) satisfactory colour television broadcasting services based on the NTSC, PAL or SECAM systems;
c)that the use of video component signals, signals consisting of the luminance and two colour difference signals, with time compression and time division multiplexing, may offer picture quality benefits, using new types of television receivers;
d)that it would add further complications to the interchange of programmes to have a greater multiplicity of systems,
recommends
1that, for a country wishing to initiate a conventional monochrome television service, a system using 525- or 625-lines as defined in Annex1 is to be preferred;
2that, for conventional monochrome 625-line systems, the video-frequency characteristic described in RecommendationITURBT.472 is to be preferred;
3that, for a country wishing to initiate a conventional colour television service, one of the systems defined in Annex1 is to be preferred.
NOTE1–Pre-1986 editions of the ex-CCIR Volumes, and in particular that of 1982, contain a complete description of systemE used in France until 1984, and systemA used in the United Kingdom until 1985.
NOTE2–Pre-1997 editions of Recommendation ITU-R BT.470 contain a complete description of the SECAM IV colour television system.
ANNEX 1
Characteristics of television systems
The following tables, given for information purposes, contain details of a number of different television systems in use at the time of the Radiocommunication Assembly, 1995.
A list of countries and geographical areas, and the television systems used, are given in Appendix1.
Information on the results of the comparative laboratory tests carried out on the various colour television systems in the period 1963-1966 by broadcasting authorities, administrations and industrial organizations, together with the main parameters of systems may be found in Reports 406 and 407,XIIth Plenary Assembly, New Delhi,1970.
All television systems listed in this Annex employ an aspect ratio of the picture display (width/height) of4/3, a scanning sequence from left to right and from top to bottom and an interlace ratio of 2/1, resulting in a picture (frame) frequency of half the field frequency. All systems are capable of operating independently of the power supply frequency.
Rec. ITU-R BT.470-51
TABLE 1
Basic characteristics of video and synchronizing signals
SystemItem / Characteristics / M / N(1) / B, B1, G / H / I / D, K / K1 / L / Rec. ITU-R
BT.472(2)
1 / Number of lines per picture (frame) / 525 / 625 / 625 / 625 / 625 / 625 / 625 / 625 / 625
2 / Field frequency, nominal value (field/s)(3) / 60
(59.94) / 50 / 50 / 50 / 50 / 50 / 50 / 50 / 50
3 / Line frequencyH and tolerance when operated non-synchronously (Hz)(3), (4) / 15750
(15734.264
0.0003%) / 15625
0.15%
(0.00014%) / 15625(5)
0.02%
(0.0001%) / 15625
0.02%
(0.0001%) / 15625
0.00002%(6) / 15625(5)
0.02%
(0.0001%) / 15625
0.02%
(0.0001%) / 15625
0.02%
(0.0001%) / 15625
0.02%
(0.0001%)
3 a) / Maximum variation rate of line frequencyvalid for monochrome transmission (%/s)(7), (8) / 0.15 / 0.05 / 0.05 / 0.05 / 0.05 / 0.05 / 0.05
Nominal and peak levels of the composite video signal (%)( (see Fig. 1)
Blanking level (reference level) / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
Peak white-level / 100 / 100 / 100 / 100 / 100 / 100 / 100 / 100
4(9) / Synchronizing level / –40 / –40
(–43) / –43 / –43 / –43 / –43 / –43 / –43
Difference between black and blanking level / 7.5 2.5(10) / 7.5 2.5
(0) / 0 / 0 / 0 / 0-7
0(11) / 0 (colour)
0-7 (mono.) / 0 (colour)
0-7 (mono.) /
Peak level including chrominance signal / 120 / 133(11) / 133 / 115(12)
133(11) / 115(12) / 124(12)
5 / Assumed gamma of display device for which pre-correction of monochrome signal is made / 2.2 / 2.2
(2.8) / 2.8(13) / (14)
6 / Nominal video bandwidth (MHz) / 4.2 / 4.2 / 5 / 5 / 5.5 / 6 / 6 / 6 / 5.0 or
5.5 or
6.0
7 / Line synchronization / see Table 1-1
8 / Field synchronization / see Table 1-2
Notes to Table 1:
(1)The values in brackets apply to the combination N/PAL used in Argentina.
(2)Figures are given for comparison.
(3)Figures in brackets are valid for colour transmission.
(4)In order to take full advantage of precision offset when the interfering carrier falls in the sideband of the upper video range (greater than 2 MHz) of the wanted signal a line-frequency stability of at least 2 10–7 is necessary.
(5)The exact value of the tolerance for line frequency when the reference of synchronism is being changed requires further study.
(6)When the reference of synchronism is being changed, this may be relaxed to 15625 0.02%.
(7)These values are not valid when the reference of synchronism is being changed.
(8)Further study is required to define maximum variation rate of line frequency valid for colour transmission. In the United Kingdom and Japan this is 0.1 Hz/s.
(9)It is also customary to define certain signal levels in 625-line systems, as follows:
Synchronizing level—0
Blanking level–30
Peak white-level100
For this scale, the peak level including chrominance signal for system D, K/SECAM equals 110.7. According to common studio operating practices, peak white-level 100 corresponds to 1.0V measured across a matched 75 termination.
(10)In Japan values are used.
(11)Value applies to PAL signals.
(12)Values apply to SECAM signals. For programme exchange the value is 115.
(13)Assumed value for overall gamma approximately 1.2. The gamma of the picture tube is defined as the slope of the curve giving the logarithm of the luminance reproduced as a function of the logarithm of the video signal voltage when the brightness control of the receiver is set so as to make this curve as straight as possible in a luminance range corresponding to a contrast of at least1/40.
(14)In Recommendation ITU-R BT.472, a gamma value for the picture signal is given as approximately 0.4.
Rec. ITU-R BT.470-51
TABLE 1-1
Details of line synchronizing signals (see Fig. 1)
Durations (measured between half-amplitude points on the appropriate edges) for various systems
Symbol /Characteristics /
M(1) /
N(2) / B, B1, G, H, I,
D, K, K1, L
(see also
Rec. ITURBT.472)
/ Nominal line period (s) / 63.492
(63.5555) / 64 / 64(3)
a / Line-blanking interval (s) / 10.2 to 11.4(4)
(10.9 0.2) / (10.24 to 11.52
(12 0.3) / 12 0.3(5)
b / Interval between time datum (OH) and back edge of line-blanking pulse (s) / 8.9 to 10.3
(9.2 to 10.3) / 8.96 to 10.24 (10.5) / 10.5(6)
c / Front porch (s) / 1.27 to 2.54
(1.27 to 2.22) / 1.28 to 2.56
(1.5 0.3) / 1.5 0.3(5), (7)
d / Synchronizing pulse (s) / 4.19 to 5.71(4)
(4.7 0.1) / 4.22 to 5.76
(4.7 0.2) / 4.7 0.2
e / Build-up time (10 to 90%) of the edges of the line-blanking pulse (s) / 0.64
0.48 / 0.64
(0.3 0.1) / 0.3 0.1
f / Build-up time (10 to 90%) of the edges of the line-synchronizing pulses (s) / 0.25 / 0.25
(0.2 0.1) / 0.2 0.1(8)
(1)Values in brackets apply to M/NTSC.
(2)The values in brackets apply to the combination N/PAL used in Argentina.
(3)In France, and some countries of the former OIRT, the tolerance for the instantaneous line period value is 0.032 s.
(4)In Japan, the values in brackets apply to studio facilities.
(5)In 625-line countries using Teletext System B as specified in Annex 1 to Recommendation ITU-R BT.653 to reduce the possibilities of data loss, the following values are preferred:
a:line blanking interval: s.
c:front porch: s.
(6)Average calculated value, for information. For system I the value is 10.4.
(7)For system I, the values are 1.65 0.1.
(8)For system I, the values are 0.25 0.05.
TABLE 1-2
Details of field synchronizing signals (see Fig. 2)
Duration (measured between half-amplitude points on the appropriate edges) for various systems
Symbol /Characteristics /
M /
N(1) / B, B1, G, H, I, D, K, K1, L
(see also Rec.
ITU-R BT.472)
/ Field period (ms) / 16.667(2)
(16.6833) / 20 / 20
j / Field-blanking interval (for H and a, seeTable11) / (19 to 21)
Ha(3) / (19 to 25) Ha
(25 Ha) / 25 Ha
j(4) / Build-up time (10 to 90%) of the edges of field-blanking pulses (s) / 6.35 / 6.35
(0.3 0.1) / 0.3 0.1
k(4) / Interval between front edge of field-blanking interval and front edge of first equalizing pulse(s) / (1.5 0.1) / 3 2(5) (systems B, D, G, K/SECAM, K1 and L only; no ref. InRec.
ITU-R BT.472)
l / Duration of first sequence of equalizing pulses / 3 H / 3 H
(2.5 H) / 2.5 H
m / Duration of sequence of synchronizing pulses / 3 H / 3 H
(2.5 H) / 2.5 H
n / Duration of second sequence of equalizing pulses / 3 H / 3 H
(2.5 H) / 2.5 H
p / Duration of equalizing pulse (s) / (2.3 0.1)(6) / 2.30 to 2.56
(2.35 0.1) / (2.35 0.1)
q / Duration of field-synchronizing pulse (s) / 27.1
(nominal value) / 26.52 to 28.16
(27.3) / 27.3(7)
(nominal value)
r / Interval between field-synchronizing pulse (s) / (4.7 0.1) / 3.84 to 5.63
(4.7 0.2) / (4.7 0.2)(8)
s / Build-up time (10 to 90%) of synchronizing and equalizing pulses (s) / 0.25 / 0.25
(0.2 0.1) / (0.2 0.1)(9)
(1)The values in brackets apply to the combination N/PAL used in Argentina.
(2)The value in brackets applies to the M/NTSC system.
(3)The value is used in Japan where is the field period.
(4)Not indicated in the diagram.
(5)This value is to be specified more precisely at a later date.
(6)The following specification is also applied in Japan: an equalizing pulse has 0.45 to 0.5 times the area of a linesynchronizing pulse.
(7)For system I: 27.3 0.1.
(8)For system I: 4.7 0.1.
(9)For system I: 0.25 0.05.
Rec. ITU-R BT.470-51
TABLE 2
Characteristics of video signal for colour television
Item / Characteristics / Colour television systemM/NTSC / M/PAL / B, B1, D, G, H, K, N/PAL / I/PAL / B, D, G, H, K, K1, L/SECAM / N/PAL(1)
2.1 / Assumed chromaticity coordinates (CIE, 1931) forprimary colours of receiver / xy
Red0.670.33
Green0.210.71
Blue0.140.08 / xy
Red0.640.33
Green0.290.60
Blue0.150.06(2)
2.2 / Chromaticity coordinates for equal primary signals / Illuminant C
x0.310
y0.316
(3) / Illuminant D65
x0.313
y0.329
(2)
2.3 / Assumed gamma value
of the receiver for which
the primary signals are
pre-corrected(4) /
2.2 /
2.8
2.4 / Luminance signal / 0.299 0.587 0.114 (5)
, and are gamma – pre-corrected primary signals(6)
2.5 / Chrominance signals (colour difference) / –0.27 –
0.74 –
0.41 –
0.48 – / 0.493 –
0.877 – / –1.902 –
1.505 –
2.6 / Attenuation of colour difference signals / dBMHz / dBMHz / dBMHz / dBMHz
Low frequency
pre-correction not
taken into account(7) / dBMHz
See Notes at the end of Table 2.
TABLE 2 (continued)
Item / Characteristics / Colour television systemM/NTSC / M/PAL / B, B1, D, G, H, K, N/PAL / I/PAL / B, D, G, H, K, K1, L/SECAM / N/PAL(1)
2.7 / Low frequency precorrection of colour difference signals / For sinusoidal signals:
ABF ()
ABF ()
signal frequency (kHz)
1 85 kHz
(See Fig. 6 for the amplitude
response)(8)
2.8 / Time-coincidence error between luminance and chrominance signals (s) / 0.05
Excluding precorrection for receiver response
2.9 / Equation of composite colour signal / EM
sin(2n 33°)
cos(2n 33°)
where:
, see item 2.4
and , see item2.5
, see item 2.11
(See also Fig. 4a) / EM sin2n cos2n
where:
, see item 2.4
and , see item 2.5
, see item 2.11
The sign of the component is the same as that of the sub-carrier burst (changing for each line) (see item 2.16 and Fig. 4b) / EM G cos 2
or EM G cos 2
alternately from line to line where:
, see item 2.4
and , see item 2.11
and , see item 2.12
and , see item 2.7
G, see item 2.13
2.10 / Type of chrominance subcarrier modulation / Suppressed-carrier amplitude-modulation of two sub-carriers in quadrature / Frequency modulation
See Notes at the end of Table 2.
TABLE 2 (continued)
Item / Characteristics / Colour television systemM/NTSC / M/PAL / B, B1, D, G, H, K, N/PAL / I/PAL / B, D, G, H, K, K1, L/SECAM / N/PAL(1)
2.11 / Chrominance sub-carrier frequency
a)Nominal value and tolerance (Hz) / 3579545 10 / 3579611.49 10 / 4433618.75 5 / 4433618.75 1(9), (10) / 4406250 2000
4250000 2000
(11) / 3582056.25 5
b)Relationship between chrominance subcarrier frequency and line frequency / Unmodulated sub-carrier atbeginning of line
282 for
272 for (12)
2.12 / Bandwidth of chrominancesidebands (quadrature modulation ofsub-carrier) (kHz) / Nominal
deviation
D* 1
(14) /
Maximum
deviation
or
Frequency deviation of chrominance sub-carrier (frequency modulation of sub-carrier) (kHz) /
(15) / 280 9
( 14) / 350 18
( 35)
–506 25
( 50)
(15) / 230 7
( 11.5) / 506 25
( 50)
–350 18
( 35)
See Notes at the end of Table 2.
TABLE 2 (continued)
Item / Characteristics / Colour television systemM/NTSC / M/PAL / B, B1, D, G, H, K, N/PAL / I/PAL / B, D, G, H, K, K1, L/SECAM / N/PAL(1)
2.13 / Amplitude of chrominance subcarrier / (16), (17) / (16) / where the peak-to-peak amplitude, 2M0 is 23 2.5 %
of the luminance amplitude (between blanking level andpeak-white)
and
where 4286 kHz and is the instantaneous subcarrier frequency.
The deviation of frequency,
, from its nominal value dueto misalignment of the circuits concerned should notexceed 20 kHz.
(See Fig. 7 for the amplitude response)
2.14 / Synchronization of chrominance sub-carrier / Sub-carrier burst onblanking back porch /
Sub-carrier burst on blanking back porch
g)Start of sub-carrier burst (s) (see Fig. 1a) / 4.71 to 5.71 (5.3nominal)
atleast 0.38s
after the trailing edge of line synchronization signal / 5.8 0.1
after epochOH / 5.6 0.1 after epochOH
(18)
h)Duration of subcarrier burst (s) (see Fig. 1a) / 2.23 to 3.11
(9 1 cycles) / 2.52 0.28
(9 1 cycles) / 2.25 0.23 (10 1 cycles) / 2.51 0.28
(9 1 cycles)
See Notes at the end of Table 2.
TABLE 2 (continued)
Item / Characteristics / Colour television systemM/NTSC / M/PAL / B, B1, D, G, H, K, N/PAL / I/PAL / B, D, G, H, K, K1, L/SECAM / N/PAL(1)
2.15 / Peak-to-peak value of chrominance sub-carrier burst
(see Fig. 1a)(19) / 4/10 of difference between blanking level and peak white-level 10% / 3/7 of difference between blanking level and peak white-level 10%
For systems D and I the tolerance is 3%
(16), (17)(16)
2.16 / Phase of chrominance
sub-carrier burst / 180 relative to
axis / 135° relative to axis with the following sign (see Fig. 4b)
(see Fig. 1a) / (see Fig. 4a)
In the NTSC / Field No.(21)
sequence of
four colour fields, / Line / 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8
field 1 is identified
in accordance with / Burst blanking sequence (see Figs. 5a and 5b)
Note (20)
(see also Fig. 5c) / I / II / III / IV / I / II / III / IV
Even
Odd / –
/ –
/
– /
– / –
/ –
/
– /
–
2.17 / Blanking of chrominance sub-carrier / Following each equalizing pulse and also during thebroad synchronizing pulses in the fieldblanking interval / 11 lines of field-blanking interval:
260 to 270
522 to 7
259 to 269
233 to 8
(see Fig. 5b) / 9 lines of the field-blanking interval:
lines311 to 319 inclusive
623 to 6 inclusive
310 to 318 inclusive
622 to 5 inclusive
(see Fig. 5a) / a)From leading edge of lineblanking signal up toi5.60.2 (s)
after epochOH,
i.e. during ci
(see Fig. 1b)(22)
b)During field-blanking interval, excluding frame identification signals, or, in countries where this is possible, during the whole of the field-blanking interval (see item 2.18)
See Notes at the end of Table 2.
TABLE 2 (continued)
Item / Characteristics / Colour television systemM/NTSC / M/PAL / B, B1, D, G, H, K, N/PAL / I/PAL / B, D, G, H, K, K1, L/SECAM / N/PAL(1)
2.18 / Synchronization of chrominance sub-carrier switching during line blanking / See item 2.16.
For signals used inprogramme integration, the tolerance on the coincidence between the reference sub-carrier and the horizontal synchronizing pulses in nominally 0 40° of the reference sub-carrier / By chrominance component of sub-carrier burst (see item 2.16) / In the SECAM system, one of two colour synchronization methods can be chosen:
–Line identification: by chrominance sub-carrier reference signals on the line-blanking back porch(23)
–By identification signals occupying 9 lines of field-blanking period:
a)line 7 to 15 in 1st and 3rd field
b)line 320 to 328 in 2nd and 4th field
(see Fig. 9)(24)
Shape of video signals corresponding to identification signals:
For lines –
Trapezoid with linear
variation from beginning of line on 155 s from 0up tolevel 1.25 and then constant at the level 1.250.06 (0.13)
(see Fig. 8)
See Notes at the end of Table 2.
TABLE 2 (continued)
Item / Characteristics / Colour television systemM/NTSC / M/PAL / B, B1, D, G, H, K, N/PAL / I/PAL / B, D, G, H, K, K1, L/SECAM / N/PAL(1)
For lines –
Trapezoid with linear variation from the beginning of the line on 186 s (2010s) from 0 down tolevel –1.52 and then constant at the level –1.520.07 (0.15)
(see Fig. 8)(15)
Peak-to-peak amplitude of identification signals:
For lines :
50050 mV
For lines :
if amplitude of luminance signal (between blanking level and peak white) equals700 mV
Maximum deviation during transmission of identification signals (kHz):
For lines :
35018
(35)
For lines :
–35018
(35)
(15)
See Notes at the end of Table 2.
Notes to Table 2:(1)These values apply to the combination N/PAL used in Argentina. Only those values are given in this column which are different from the values given in the column B, G, H, N/PAL.
(2)For SECAM systems and for existing sets, it is provisionally allowed to use the following chromaticity coordinates for the primary colours and white:
xy
Red0.670.33
Green0.210.71
Blue0.140.08
White0.3100.316(C-white)
(3)In Japan, the chromaticity of studio monitors is adjusted to a D-white at 9300 K.
(4)The primary signals are pre-corrected so that the optimum quality is obtained with a display having the indicated value of gamma.
(5)In certain countries using the SECAM systems and in Japan it is also permitted to obtain the luminance signal as a direct output from an independent photo-electric analyser instead of from the primary signals.
(6)For the SECAM system, it is allowable to apply a correction to reduce interference distortions between the luminance and chrominance signals by an attenuation of the luminance signal components as a function of the amplitude of the luminance components in the chrominance band.
(7)This value will be defined more precisely later.
(8)The maximum deviations from the nominal shape of the curve (see Fig. 6) should not exceed 0.5 dB in the frequency range from 0.1 to 0.5 MHz and 1.0 dB in the frequency range from 0.5 to 1.3 MHz.
(9)When the signal originates from a portable or overseas source the tolerance on the frequency may be relaxed to 5 Hz. Maximum rate of variation of 0.1 Hz/s. / (10)This tolerance may not be maintained during such operational procedures as “genlock”.
(11)A reduction of the tolerance is desirable.
(12)The initial phase of the sub-carrier undergoes in each line a variation defined by the following rule:
From frame to frame: by 0: 180: 0: 180: and so on, and also from line to line in either one of the following two patterns:
0: 0: 180: 0: 0: 180: and so on,
or0: 0: 0: 180: 180: 180: and so on.
(13) 1300 kHz is adopted in the People’s Republic of China.
(14)The unity value represents the amplitude of the luminance signal between the blanking level and the peak white-level.
(15)Provisionally, the tolerances may be extended up to the values given brackets.
(16)During transmission of a monochrome programme of significant duration, in order to ensure satisfactory operation of colour-killers in receivers, all signals having the same nominal frequency as the colour sub-carrier that appears in the line-blanking interval, should be attenuated by at least 35 dB below the peak-to-peak value of the burst given in item 2.15, column 3 of Table 2, and shown as item 5 in Fig. 1.
(17)The value given in Note (16) is accepted on a tentative basis.
(18)Transmitter pre-correction for receiver group delay is not included.
(19)For the use of automatic gain control circuits, it is important that the burst amplitude should maintain the correct ratio with the chrominance signal amplitude.
Notes to Table 2:
(20)Field 1 of the sequence of four fields in the NTSC video signal is defined by a whole line between the first equalizing pulse and the preceding horizontal synchronizing pulse and a negative-going zero-crossing of the reference sub-carrier nominally at the 50% point of the first equalizing pulse. The zero-crossing of the reference sub-carrier shall be nominally coincident with the 50% point of the leading edges of all horizontal synchronizing pulses for programme integration at the studio.
(21)Field 1 of the sequence of eight colour fields is defined as that field, where the phase of the extrapolatedcomponent (see item 2.5 of Table 2) of the video burst at the hall amplitude point of the leading edge of the line synchronizing pulse of line 1 is in the range–90° 90°.
(22)The value of the tolerance will be defined more precisely later. / (23)The line identification method is preferable, because it will enable agreements to be reached subsequently on the suppression of frame identification signals in international programme exchanges. In the absence of such agreements, signals meeting the SECAM standard are regarded as comprising such identification signals.
In France, a decree of 14 March 1978 specified that colour TV receivers placed on sale on or after 1 December 1979 must use the line identification method of decoding. In France and Ukraine, studies are taking place with a view to reducing the number of lines used for field colour identification signals.
(24)The order in which the identification signals DR* and DB* appear on the four fields of a complete cycle given in Fig. 9 is in conformity with Recommendation ITU-R BR.469.
TABLE 3